In order to further solve the problem of data service requirement of a wireless cellular network, 3GPP (The 3rd Generation Partnership Project) proposed, in the latest LTE-A evolution version Release 12, a solution for denser small cell deployment. By deploying small cells, a system throughput can be improved, a more effective coverage can also be provided, so as to realize a load balancing. In a whole LTE-A network, the small cells are mainly deployed in the following three scenarios: deployed with a frequency same as a macro base station, deployed with a frequency different from a macro base station, or deployed without a macro base station. In a scenario of being deployed in the frequency different from the macro base station, the small cell operates with a frequency different from the macro base station, and thus cross-layer interference between the macro base station and the small cell may be ignored, which is consistent with the research method for the scenario of deployment without a macro base station. Therefore, from a perspective of network interference analysis, the small cell deployment may be classified into two types: a same-frequency deployment with only cross-layer interference between the small cell and the macro base station, and a different-frequency deployment with only same-layer interference. And the different-frequency deployment of the small cell is a hotspot in 3GPP research.
Although a dense small cell deployment can greatly improve the spectrum efficiency of a network, it may bring serious same-layer interference, and increase the operation cost. In another aspect, interference of a small cell network, especially interference in a dense deployment, is a bottleneck of a further improvement of system performance. Therefore, interference management and energy efficiency are currently research focuses of a small cell project group of 3GPP. In a case of the different-frequency deployment, that is, in a case that the cross-layer interference between the macro base station and the small cell is not taken into account, the dense deployment of small cells may make a user equipment be interfered by many other small cells at the same time. Therefore, the same-layer interference is a main constraint on system performance improvement.